The new image encryption algorithm based on Logistic chaotic map is designed. First, after two initial values of Logistic chaotic map are pretreated, two of the modified initial values are obtained based on which two chaotic sequences are generated. Next, taking the first n-gray value of the original image in turn, pixel gray value (n is odd and even) is respectively encrypted by the chaotic sequence generated by two key. Results and analysis of experiment show that the proposed scheme has higher security.